Methods for reclaiming developing solvents
The present invention relates to an improved method for reclaiming and recycling developing solvents used in the production of flexographic printing plates. More specifically, the invention relates to reclaiming and/or recycling of the developing solvent through centrifugation and/or filtration. According to the invention, the solvent used in developing printing plates can be reclaimed and/or recycled by simply centrifuging the polymer-contaminated solvent. In certain embodiment, the centrifuged solvent is further filtered. The process involves transferring the contaminated solvent, from a plate processor or a dirty holding tank, to a centrifuge, and centrifuging the contaminated solvent to remove the polymer. The reclaimed solvent can be transfer directly back to the plate processor or to a clean holding tank.
1. A method for purifying polymer-containing solvent used in developing printing plates, said method comprising the steps of centrifuging said solvent to separate the polymer from the solvent, wherein the solvent is selected from the group consisting of terpene esters, terpene ethers, alkyl esters, substituted benzenes, and combinations thereof.
2. The method of claim 1 , wherein the steps comprises a continuous process.
3. The process of claim 1 , wherein the process is a batch process.
4. The method of claim 1 , wherein the polymer is selected from the group consisting of block co-polymers of styrene and butadiene, block co-polymers of styrene and isoprene, co-polymers of butadiene and acrylonitrile, terpolymers of butadiene, acrylonitrile, and acrylic acid.
5. The method of claim 1 , wherein said solvent further comprises a co-solvent.
6. The method of claim 5 , wherein the co-solvent is selected from the group consisting of n-butanol, 2-ethoxyethanol, benzyl alcohol, ethanol, methanol, propanol, isopropanol, alpha terpineol, dipropylene glycol methyl ether, 2-butoxyethanol, isopropyl alcohol, and 2-(2-butoxyethoxy) ethanol, cyclopentanol, cyclohexanol, cycloheptanol, substituted cyclopentanol, substituted cyclohexanol, substituted cycloheptanol, cyclopentyl substituted alcohol, cyclohexyl substituted alcohol, and cycloheptyl substituted alcohol.
7. The method of claim 6 , wherein the substituted cyclohexanol is 4-ethycyclohexanol.
8. The method of claim 7 , wherein the substituted cyclopentanol is 2,3 dimethylcyclopentanol.
9. The method of claim 7 , wherein the cyclohexyl substituted alcohol is cyclohexyipropanol.
10. The method of claim 7 , wherein the cyclopentyl substituted alcohol is 4-cyclopentylpentanol.
11. The method of claim 1 , wherein said solvent further comprises a non-solvent.
12. The method of claim 11 , wherein the non-solvent is selected from the group consisting of aliphatic petroleum distillates, naphthas, paraffinic solvents, hydro-treated petroleum distillates, mineral oil, mineral spirits, ligroin, decane, octane, and hexane.
13. The method of claim 12 , wherein the paraffinic solvents are isoparaffins.
14. The method of claim 1 , wherein the centrifuge is a bowl disc centrifuge with conical discs.
15. The method of claim 1 , wherein the centrifuging step is performed at g forces of at least about 4000.
16. The method of claim 1 , wherein the solvent is maintained at about 70° F.
17. The method of claim 1 , further comprising the step of adding a precipitant or co-polyrnerizing material to the solvent.
18. The method of claim 1 , further comprising the step of radiating the solvent with a wavelength of light appropriate to crosslink the polymer.
19. The method of claim 1 , further comprising the step of filtering the solvent.